Must vs Have To / Has To

Must and have to express obligation or necessity:

The main differences between must and have to are:

Must means "really should or else it will be bad for you", it expresses an obligation forced by the speaker.

Have / Has to expresses general obligations. When we are talking about another person's obligation we use have to, too. We use have to when the obligation comes from outside.

See Modals Chart / Modals Exercises

See Subject Exercises:

Must vs Have/Has To Exercise 1
Must vs Have To Exercise 2
Mustn't vs Don't Have to
Must/Mustn't vs Needn't vs Have to

Examples Sentences

Teacher : You must listen to me carefully.
Father : You must stop smoking.

You have to put on uniform at school.
She has to buy new dictionary for school.
You have to give your report by 5 p.m. tomorrow.
They have to wake up early in the morning.


Affirmative FormSubject + must + verb + complement
You must come home before 8 o'clock.
Negative FormSubject + mustn't + verb + complement
You mustn't come home before 8 o'clock.
Question FormMust + subject + verb + complement ?
Must you come home before 8 o'clock?
Negative Question FormMustn't + subject + verb + complement ?
Mustn't you come home before 8 o'clock?


Affirmative FormSubject + has to / have to + verb + complement
He has to take his medicine.
Negative FormSubject + don't have to / doesn't have to + verb + complement.
He doesn't have to take his medicine.
Question FormDoes / Do + subject + have to + verb + complement ?
Does he have to take his medicine?
Negative QuestionDoesn't / Don't + subject + have to + verb + complement ?
Doesn't he have to take his medicine?


When we say he doesn't have to take his medicine, we mean that he is not obligated to take his medicine. (Lack of necessity)

We say he mustn't take his medicine to give it a negative obligation meaning.


Must is only used in present and future meanings. Have to can be used in any tenses.


Must also has a probability meaning.

He missed the class for the first time, he must be sick.

Similar Subjects:

Needn't Have Done (Verb3) vs Didn't Need To
Auxiliary Verbs
Modal Verbs Chart

GrammarBank Video Exercises
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